BitlBee allows users to talk to people on the major instant messaging and microblogging networks (including MSN, Google Talk, AIM, and Twitter) from within any IRC client by emulating an IRC server. Virtual channels are created with all of the user's contacts in them, who can be talked to in the channel or in a query. Also, one can participate in group chats and chat rooms like they were normal IRC channels.

Instantbird is a multi-protocol instant messaging
client. Using it, you can connect to all your
different IM accounts. It uses the Mozilla
rendering engine to display messages, and uses the
Pidgin libpurple to connect to the different
networks.

Pidgin is a GTK2-based instant messenger application. It supports multiple protocols via modules, including AIM, ICQ, Yahoo!, MSN, Jabber, IRC, Napster, Gadu-Gadu and Zephyr. It has many common features found in other clients, as well as many unique features. Pidgin is not endorsed by or affiliated with AOL TimeWarner, Microsoft, or Yahoo.

Licq includes all the basic features of ICQ, like sending/receiving messages, chat, file transfer, contact list with pixmaps and user status, basic/extended user info, adding/editing users from within the GUI, user history, user groups, and new user registration. All commands and information are available through a simple and convenient tab dialog. Licq also has a completely configurable user interface with Skin and Icon pack support. It is written in C++ and comes with a GUI plugin using the Qt widget set. Other plugins are also available, like basic MSN support.

climm (CLI-based Multi-Messenger) is a portable, small, yet powerful console-based ICQ and XMPP client. It supports password changing, auto-away, creation of new accounts, and other features that makes it a very complete yet simple client. It is able to send and receive messages from the ICQ network, list users that are offline and online (including their online status), search for users by email address, and look up basic (name, UIN, email) information. climm was formerly known as mICQ.

sim (simple instant messaging) is an IRC client
specialized for use with bitlbee. It is based on
sic (http://suckless.org). It reads commands from
standard input and prints all server output to
standard output. It also multiplexes all channel
traffic into one output, so you don't have to
switch to different channel buffers. sim must be
customized by editing its source code to insert
the correct username, server, password, and
identification information.

JClaim is an instant message client, tools, and
development framework. It supports AIM, ICQ,
Yahoo!, MSN, Jabber, Google Talk, and SMS. The
framework can be used for designing your own
tools. The UI includes spell checking and a lot
more. A Web interface is included for remote
access.

Claros inTouch is an AJAX Web mail, instant messenger, address book, and note taker application. The main features are drag and drop support, background attachment uploading, built-in Bayesian spam protection that can identify junk mail on the fly, folder support for the POP3 protocol, compatibility with any POP3/IMAP and SMTP server, operating system independence, support for sending HTML email, and full MIME compatibility. It also features a unique AJAX instant messenger that is capable of talking with a Jabber server.

pidgin-osd is an application that uses the xosd
library to print various events on the X root
window on receiving incoming messages from pidgin.
It is based on gaimnosd 0.7 (the last publically
available version). It is mostly like the gaimnosd
plugin; the only difference is that an
implementation for UTF-8 conversion to the current
used locale was added.